STEER/AliMixedEvent.cxx

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   3  *                                                                        *
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  15
  16 /* $Id$ */
  17
  18
  19 //-------------------------------------------------------------------------
  20 //                          Class AliMixedEvent
  21 // VEvent which is the container of several VEvents
  22 // Use Case: Event Mixing
  23 // Origin: Andreas Morsch, CERN, Andreas.Morsch@cern.ch
  24 //-------------------------------------------------------------------------
  25
  26
  27 #include "AliMixedEvent.h"
  28 #include "AliESDVertex.h"
  29 #include "AliExternalTrackParam.h"
  30 #include "AliESDtrack.h"
  31 #include "TVector3.h"
  32 #include "AliVVertex.h"
  33 #include <TMath.h>
  34 #include <TMatrix.h>
  35 #include <TMatrixD.h>
  36
  37 ClassImp(AliMixedEvent)
  38
  39
  40 AliMixedEvent::AliMixedEvent() :
  41     AliVEvent(),
  42     fEventList(),
  43     fNEvents(0),
  44     fNumberOfTracks(0),
  45     fNTracksCumul(0),
  46     fMeanVertex(0)
  47 {
  48     // Default constructor
  49 }
  50
  51 AliMixedEvent::AliMixedEvent(const AliMixedEvent& Evnt) :
  52     AliVEvent(Evnt),
  53     fEventList(),
  54     fNEvents(0),
  55     fNumberOfTracks(0),
  56     fNTracksCumul(0),
  57     fMeanVertex(0)
  58 { } // Copy constructor
  59
  60 AliMixedEvent& AliMixedEvent::operator=(const AliMixedEvent& vEvnt)
  61 { if (this!=&vEvnt) {
  62     AliVEvent::operator=(vEvnt);
  63   }
  64
  65   return *this;
  66 }
  67
  68
  69 void AliMixedEvent::AddEvent(AliVEvent* evt)
  70 {
  71     // Add a new event to the list
  72     fEventList.AddLast(evt);
  73 }
  74
  75
  76 void AliMixedEvent::Init()
  77 {
  78     // Initialize meta information
  79     fNEvents = fEventList.GetEntries();
  80     fNTracksCumul = new Int_t[fNEvents];
  81     fNumberOfTracks = 0;
  82     TIter next(&fEventList);
  83     AliVEvent* event;
  84     Int_t iev = 0;
  85
  86     while((event = (AliVEvent*)next())) {
  87         fNTracksCumul[iev++] = fNumberOfTracks;
  88         fNumberOfTracks += (event->GetNumberOfTracks());
  89     }
  90 }
  91
  92
  93 AliVParticle* AliMixedEvent::GetTrack(Int_t i) const
  94 {
  95     // Return track # i
  96     Int_t iEv  = TMath::BinarySearch(fNEvents, fNTracksCumul, i);
  97     while((iEv < (fNEvents - 1)) && (fNTracksCumul[iEv] == fNTracksCumul[iEv+1])) {iEv++;}
  98
  99     Int_t irel = i - fNTracksCumul[iEv];
 100     AliVEvent* evt = (AliVEvent*) (fEventList.At(iEv));
 101     return (evt->GetTrack(irel));
 102 }
 103
 104 const AliVVertex* AliMixedEvent::GetEventVertex(Int_t i) const
 105 {
 106     // Return track # i
 107     Int_t iEv  = TMath::BinarySearch(fNEvents, fNTracksCumul, i);
 108     while((iEv < (fNEvents - 1)) && (fNTracksCumul[iEv] == fNTracksCumul[iEv+1])) {iEv++;}
 109     AliVEvent* evt = (AliVEvent*) (fEventList.At(iEv));
 110     return (evt->GetPrimaryVertex());
 111 }
 112
 113 void AliMixedEvent::Reset()
 114 {
 115     // Reset the event
 116     fEventList.Clear();
 117     fNEvents = 0;
 118     fNumberOfTracks = 0;
 119     if (fNTracksCumul) {
 120         delete[]  fNTracksCumul;
 121         fNTracksCumul = 0;
 122     }
 123 }
 124
 125 Int_t AliMixedEvent::EventIndex(Int_t itrack)
 126 {
 127   // Return the event index for track #itrack
 128   return  TMath::BinarySearch(fNEvents, fNTracksCumul, itrack);
 129 }
 130
 131 void AliMixedEvent::ComputeVtx(TObjArray *vertices, Double_t *pos,Double_t *sig){
 132 //
 133 // Calculate the mean vertex psoitions from events in the buffer
 134
 135     Int_t nentries = vertices->GetEntriesFast();
 136     Double_t sum[3]={0.,0.,0.};
 137     Double_t sumsigma[6]={0.,0.,0.,0.,0.,0.};
 138
 139     for(Int_t ivtx = 0; ivtx < nentries; ivtx++){
 140         AliVVertex *vtx=(AliVVertex*)vertices->UncheckedAt(ivtx);
 141         if(!vtx) return;
 142         Double_t covariance[6];
 143         vtx->GetCovarianceMatrix(covariance);
 144         Double_t vtxPos[3];
 145         vtx->GetXYZ(vtxPos);
 146         if(covariance[0]==0) continue;
 147         sum[0]+=vtxPos[0]*(1./covariance[0]);
 148         sumsigma[0]+=(1./covariance[0]);
 149         if(covariance[2]==0) continue;
 150         sum[1]+=vtxPos[1]*(1./covariance[2]);
 151         sumsigma[2]+=(1./covariance[2]);
 152         if(covariance[5]==0) continue;
 153         sum[2]+=vtxPos[2]*(1./covariance[5]);
 154         sumsigma[5]+=(1./covariance[5]);
 155         if(covariance[1]==0) continue;
 156         sumsigma[1]+=(1./covariance[1]);
 157         if(covariance[3]==0) continue;
 158         sumsigma[3]+=(1./covariance[3]);
 159         if(covariance[4]==0) continue;
 160         sumsigma[4]+=(1./covariance[4]);
 161     }
 162
 163     for(Int_t i=0;i<3;i++){
 164         if(sumsigma[i]==0) continue;
 165         pos[i]=sum[i]/sumsigma[i];
 166     }
 167     for(Int_t i2=0;i2<6;i2++){
 168         if(sumsigma[i2]==0) {sig[i2]=0.; continue;}
 169         sig[i2]=1./sumsigma[i2];
 170     }
 171     return;
 172 }
 173